1. Field of the Invention
Aspects of the present invention relate to an organic light-emitting device and a method of manufacturing the same. More particularly, aspects of the present invention relate to an organic light-emitting device that includes a transparent conducting oxide layer as a cathode and a method of manufacturing the organic light-emitting device.
2. Description of the Related Art
Generally, organic light-emitting devices include an anode, an organic light-emitting layer disposed on the anode, and a cathode disposed on the organic light-emitting layer. When a voltage is applied between the anode and the cathode, holes from the anode are injected into the organic light-emitting layer, and electrons from the cathode are injected into the organic light-emitting layer. The holes and the electrons injected into the organic light-emitting layer are recombined to generate excitons, emitting light upon transition of the excitons from an excited state to a ground state.
Organic light-emitting devices are largely classified into a bottom-emission type wherein light emitted from an organic light-emitting layer is transmitted through a lower substrate and a top-emission type wherein light emitted from an organic light-emitting layer is transmitted through an upper substrate. Top-emission type organic light-emitting devices have the advantage of having a higher aperture ratio than bottom-emission type organic light-emitting devices.
In top-emission type organic light-emitting devices, a cathode, which is a light-transmissive electrode, is formed as a metal layer having a low work function so as to provide electron injection characteristics, e.g., an MgAg layer. However, a metal cathode exhibits great reflectivity with respect to light at a visible light wavelength region. Thus, top-emission type organic light-emitting devices including a metal cathode essentially have a microcavity structure. Such a microcavity structure causes a luminance change and a color shift as a function of viewing angle. Moreover, because of the microcavity structure, it is necessary to strictly control the thickness of various organic functional layers, including the organic light-emitting layer, within a film uniformity range of 2% or less. This seriously hinders the mass production of organic light-emitting devices.